
public class lioain {
    public static void main(String[] args) {
        //1.创建对象
        StringBuilder sb = new StringBuilder("abc");

        //2.添加功能
        sb.append("def").append("ghi").append("jkl").append("mno");
        System.out.println(sb);
        String s = sb.toString();
        System.out.println(s);

    }
}
